This invention concerns an endoscope using an image pickup element which can separate the light from the light source into multiple various wavelength regions, irradiate them to a subject, correct the spectral characteristics of the image signals obtained by the image pickup element and display the picture in accordance with the wavelength region of the subject and waveform image analyzed.
Generally, the endoscope is used to observe inside the cavity of a living body or mechanical component.
Conventionally, in such an endoscope, the image of a subject is introduced out by means of the optical fiber bundle and the optical image formed on the irradiating end face of the optical fiber bundle is observed through the eye lens system. In another equipment already developed, an image pickup element such as charge coupled device (CCD) is provided at the end position of the axis of the endoscope in place of the above optical fibers and the optical image formed on the light receiving face of the image pickup element is converted into electrical signals, introduced out of the body cavity or component cavity through the signal line, and displayed on a television monitor after necessary signal processing. In such endoscope, the light source unit to illuminate the subject is usually installed outside the endoscope and the light from the light source unit is introduced to the end of the inserting member of the endoscope through the light source connection and light guide of the endoscope.
In the aforementioned endoscope, however, the light irradiated from the light source unit through the light guide includes the lights of various wavelength regions of 400-3000 nm and the information obtained from the subject also corresponds to the various wavelength regions, and therefore, it is impossible to observe restricting to a particular wavelength region.
That is, in the case of the former optical observation, the subject is observed directly with the naked eye through the optical lens, and therefore, the information obtained corresponds to the range of the visible wavelength region of the illuminating light, and in the case of the picture observation using the image pickup element, the image pickup element can sense the light in other regions than the visible ray wavelength such as infrared wavelength region and the information obtained corresponds to the range of the wavelength regions including such invisible ray wavelength.
By the way, if a part to be observed is an internal organ of man, the energy reflected or absorbed for each wavelength region of the light irradiated differs, for example, from stomach to blood. For example, in order to recognize a tissue similar to blood in the stomach or part which contains a lot of blood, the difference is more clearly seen by comparing them in the near infrared wavelength region.
Therefore, in the conventional endoscopes which observe in a wide wavelength range including the visible ray wavelength region, it required a high degree of knowledge and experience and a lot of time and labor to determine and recognize the difference between the affected part and normal part of the living body by means of the image observed.